1. Technical Field
The invention relates to a contact device for transmitting electrical signals between a lock and key in a cylinder lock with a stator housing. A rotor is arranged therein with mechanical holding devices and a key channel having a portion in which contact elements for the signal transmission are present, as well as a key with an integrated electronic information carrier. On the key barb in a portion beside the mechanical codings, contact points are arranged.
2. Description of the Prior Art
Cylinder locks of this kind are used where the security of the known, purely mechanical cylinder locks no longer satisfy the requirements, and additional electronic security means are arranged both on the key and on the lock. Setting the key to such cylinder locks with at least one memory element which contains a magnetic or electronic code, is known. In this lock is a corresponding reading device which may consist of a simple electronic reading unit or one or more microprocessors. For transmitting the stored data from the key to the lock, optical, inductive or mechanical contact elements may be used. The key and cylinder lock in such locking devices are exposed to many disturbing influences, such as soiling, deformation, strong magnetic fields, etc., and there are often disturbances in use with such locks and keys set with added electronic elements. This occurs especially where the transmission of the stored data takes place through optical or inductive contact elements.
Keys and locks in which electronic elements with security information are combined with mechanical holding devices or codings have only been in widespread use quite recently. It has been found that the use of mechanical contacts assures the highest security in the transmission of signals. Because of the high degree of miniaturization of the known mechanical cylinder locks, and the needed long life of contact parts between lock and key, the shaping of contact elements in locks presents extremely great difficulties. Most of the contact elements known today do not satisfy in cylinder locks. Such a cylinder lock with security in cylinder locks. Such a cylinder lock with the respective key is known from German Patent No. 3,245,681. In the key described there, incisions are arranged on the key barb in which pin holding devices engage when the key is inserted in the lock. These pin holding devices are supported in a rotor which can rotate in the stator housing of the cylinder lock. If the key incisions agree with the penetration depth of the pin holding devices, the mechanical blocking between rotor and stator housing is removed. In addition to this mechanical coding or holding, at the end of the key barb is arranged an electronic security system. For this, there is present on the key barb a data carrying ring, for example, in the form of a magnetic strip or with a light or electrooptical point or strip screening. In the lock is arranged, in the portion of the data carrier on the key, a reading head which, without contact, produces the contact for the passage of information between key and lock. This contact or reading unit decodes the data contained on the key and checks it for agreement with the data stored in the lock. If there is agreement, then through an electromagnet and a blocking element, the rotary movement of the rotor is released, and the lock can be opened. In this arrangement, the number of possible locking variations, through the superimposing of the electronic system on the mechanical, is greatly increased. But the system described here is extremely prone to disturbance since foreign particles may collect on the data carrier on the key barb. The transmission of data between key and lock is disturbed or even prevented. Also, the data stored on the data carrier on the key barb may be changed through strong magnetic fields or other external influences, purposely or involuntarily. In this way, this lock-and-key system greatly loses in security and is extremely prone to disturbances. Disturbances in the electronic portion have the effect that the lock, even with agreement of the mechanical coding between key and lock, can no longer be opened since the rotor remains blocked electromechanically. If this blocking is released by bridging over the electronic system, the security of the lock is limited to that of a purely mechanical coded lock and key system.
A lock and key system is known from German Patent No. 3,006,128 A1, in which the information is transmitted from the key to the lock through a mechanical contact device. In this device, an electronic circuit is placed in the key barb portion of the key, which contains among other things, memory units for electronic codings. On the key barb are arranged contact rings which are connected with the electronic circuit. The receiving housing for the key contains slide contacts which, with the key completely inserted, lie against the contact surfaces on the key barb. Beside the key housing is arranged a lock which can be actuated electromagnetically and which is controlled by a locking control such as a microprocessor for example. With agreement of the data stored in the electronics of the key with the allowing conditions in the control of the lock, this opens the electromagnetic lock. It is apparent that the mechanical contact arrangement in the form of a coaxial catch plug, like that shown here, can be used only with difficulty on a mechanical cylinder lock with the known miniature construction. Coaxial plugs of this kind are bulky and do not meet the requirements as to long life and security, as demanded in mechanical cylinder locks.
From U.S. Pat. No. 4,379,966 can be seen another contact system with slide contacts. Here the contact springs are arranged on an elastic bearing plate which also has conductor paths. This elastic plate is placed around a part of the stator of the lock, and is fastened into the desired position with the aid of complicated parts pushed one into another. This lock also has no mechanical blocking elements. Rather, electric signals can only be provided by a data carrying key. It is apparent that the contact device cannot be built into a known mechanical cylinder lock, since the solution shown is too complicated and too bulky and takes up the whole circumference of the stator.